Men with advanced prostate carcinoma are frequently subjected to estrogen therapy or castration empirically without any information concerning the steroid binding capacity of their tumor, though it is known that only 80% of patients will respond. Conventional biochemical receptor assays of human prostate cancer are costly, difficult to perform and interpret and require radiochemicals and sophisticated equipment. Such assays do not allow for distinction of the source of receptor possibly from benign as well as malignant tissue components, or an estimate of tumor cell steroid binding heterogeneity. The purpose of this project is to expand experience with histochemical and immunohistologic methods for detection of estrogen and androgen binding in prostatic carcinoma. Histochemical analyses of androgen binding have shown significant correlations with biochemical analyses for androgen receptor and may be of value in predicting the clinical response to hormonal therapy. These assays are simple to perform, inexpensive and allow distinction between binding in benign and malignant elements, assessment of tumor cell binding heterogeneity and determination of intracellular localization of binding in nucleus and/or cytoplasm, all in one step. Correlation with biochemical assays for androgen receptor will continue. Additionally, correlations with estrogen receptor biochemical assays will be made. Correlation of all results with objective response to hormonal therapy will continue. Monoclonal antibodies to estrogen receptor will also be employed in immunohistologic studies and results included in these correlations. Thus both estrogen binding and receptor antigenicity will be assessed and compared.